Conventionally, the semiconductor laser oscillator is frequently utilized for the purpose of excitation of a solid state laser and fiber laser, and a processing machine with a direct diode laser (DDL) to be used directly in processing is widespread due to the achievement of high luminance. As the DDL oscillator, there is an oscillator using a plurality of single emitter laser diodes with a high output. This DDL oscillator emits a laser in which spectral beams are coupled by locking to respective ones of a plurality of wavelengths.
In the DDL oscillator configured from single emitter laser diodes, it is common to divide a plurality of laser diodes into a plurality of banks, and control them such that an identical current value will flow in each bank. In one bank, 30-40 pieces of laser diodes are connected in series, for example.